Frank Nitti has a major problem: someone in his organization is leaking information to Eliot Ness and the Untouchables. They've closed down several of his distilleries and several members of the organization are starting to question Nitti's leadership. He decides to seek out someone who use to work for Al Capone, Walter Trager known as the Leaker, who has a knack for finding and closing down leaks in the organization.